This invention pertains to image copiers and, more particularly, to a multi-purpose copier/printer having duplex printing capability.
Traditionally, office environments have been provided with photocopiers for making exact imagery productions of documents, printers for printing documents from computers, and facsimile machines for sending and receiving facsimiles. With the advent of digital office equipment, it has been recognized that each of these pieces of office equipment merely handles a digital file. Therefore, recent efforts have been made to combine two or more of these office machines into a single machine. Such a machine has been termed a xe2x80x9cmopierxe2x80x9d by one manufacturer. The distinguishing characteristics of these machines are that they are provided with a digital printer which is configured to receive a digital print file and print the file onto a sheet of printable medium such as paper. Information to be printed can be, for example, a digital file sent directly from a personal computer to the printer, a document which is scanned and digitized and then sent in a digital form to the printer, or a file which can be received over a telephone line in analog or digital form, converted into a digital form, if necessary, and then printed, such as is done for facsimiles.
Users frequently desire to print documents in a duplex format. Duplex copying includes reproducing an original document which has matter printed on both sides of a single page so that the final product appears in a nearly identical format as the original product. Duplex copying also includes reproducing a single side from two sheets of a document onto both sides of a single sheet in the final product. The first example of duplex copying is known as 2xe2x86x922 copying, since a dual-sided original is reproduced as a dual-sided copy. The second example of duplex copying is known as 1xe2x86x922 copying, since single-sided originals are reproduced as double-sided copy products.
Modern printers and copiers are frequently provided with a laser copying element. In order to handle the rather large digital files which are required to faithfully reproduce an original file, substantial computer readable memory is typically also provided with the printer, In traditional duplex copying, an original multiple page document is deposited face up in a document feeder. This means that the last page of the document will be the first page processed by the document feeder. This configuration is not only traditional in digital copiers, but in analog copiers as well. Thus, in the prior art, when a user selected duplex copying, all pages of the document were first scanned, and the scanned images saved in a computer readable memory. After scanning the full document, a processor within the copier electronically assembled the pages for duplex reproduction. Copying then began by printing the first page of the document, the second page of the document, etc. In analog copiers, for a multi-copy print job, the original image is typically scanned as many times as there are number of copies to be made. Also, analog copiers typically require pages to be accumulated in an internal holding bin so that all front sides are first printed and accumulated, and then the backsides are printed. Thus, the first sheet of copy product will not be produced until at least all front sides are scanned and printed. This significantly reduces the time-to-first-copy of the copy product. While some electrostatic copiers may have provided for first page scanning followed by first page printing prior to scanning the entire document, no copier in which the image is first saved as an electronic data file provided such a feature. This significantly reduces the time between the moment a document is submitted for scanning and the first page is printed. However, for a variety of reasons, it is desirable that the time between the scanning of the first sheet of a document and the printing of the first page of the copy be minimized.
FIG. 1 shows a diagram of the prior art method of 2xe2x86x922 duplex copying showing how both sides of a first sheet C are first scanned, both sides of a second sheet B are first scanned, and so on, until all sides of the document are scanned. In the traditional xe2x80x9cface upxe2x80x9d original receiving tray of the scanner, the last page of the document is scanned first, on through the first page being scanned last, as indicated in FIG. 1. In FIG. 1, sides Nxe2x88x921 and N represent the two sides of the last sheet C of the document. Thereafter, the first page of the document M is printed, second page P, and so on until the final page L is printed. In like manner, FIG. 2 shows a diagram of the prior art method of printing a 1xe2x86x922 duplex copy. The sheets of the original document are all first scanned in a single-side, face-up scan mode, beginning with the last sheet C and continuing on through sheet A. Thereafter, the duplex copies are printed, beginning with the two first sides of the two first sheets of the original document being printed on sides one and two of the first sheet M of the copy product, and so on until the first sides of the penultimate sheet D and last sheet C of the original document are printed on the two sides of the last sheet L of the copy product.
In electrostatic or photostatic copy devices, the sheets in the printing of the copy product are typically handled one page at a time. Contrariwise, multipurpose copiers are configured to first receive the entire document as an electronic data file and store the document onto a computer readable memory such as a hard disk or RAM. Thereafter, the copies are printed in accordance with user instructions for a selected copy product. For example, the multi-purpose copier may be connected to a personal computer. The user may request that five copies of a document from the user""s computer be printed by the copier/printer. In a traditional printer configuration, the user""s computer would send five separate copy requests to the printer. With the multi-purpose copier/printer, a single print request for five copies is sent to the printer. The electronic file is stored on a memory device such as a hard drive. Five copies of the document are then printed from the internal memory of the copier/printer. It is because of this architecture that duplex copies are traditionally printed after all sheets have been scanned by the scanner, as opposed to the traditional method of printing duplex copies from an electrostatic copier.
Since the multi-purpose copier/printer (mopier) is configured to receive documents from several sources, including an original hard copy document scanner, it is not configured to provide first page scanning followed by first page printing. It is, therefore, desirable to provide a multi-purpose copier/printer having the capability to scan and, subsequently, print a first page of a document prior to scanning all subsequent pages of the original document and, more particularly, to provide this feature in a duplex mode.
In a first aspect of the invention, an image copier comprises a scanner configured to electronically scan a first page side, a second page side, and a third page side of an original document comprising at least two pages. The scanner is further configured to produce an electronic data stream comprising discrete electronic representations of the individual page sides of the document. The image copier has a printer configured to print the discrete electronic representations of the first and second page sides of the document as a duplex page of copy product prior to completing the scanning of the third page side of the document.
More specifically, in one embodiment the scanner produces an electronic data stream comprising discrete electronic representations discretized according to the page side scanned. The copier can further include a computer readable memory. The image can also have a copy processor configured to receive user inputs which define a copy product to be produced by the copier from the electronic data stream which is provided by the scanner. The copy processor can be configured to receive the discrete electronic representations of the page sides of the document and build discrete digital representations of the page sides therefrom. These digital representations of the page sides can be stored in the computer readable memory. The image copier can further comprise an image processor configured to receive the digital representations of the page sides of the document from the computer readable memory and arrange these digital representations into a print-engine readable data set which represents the page sides of the document.
In another embodiment the image copier has a print engine configured to receive the print-engine readable data set of the page sides of the document and convert the print-engine readable data set into a set of electronic signals which are usable by a print element to print a final copy product. The image copier includes the print element, which is configured to receive such signals and produce a copy product containing images of page sides of the document in response to a command from the copy processor, which includes a designation of the copy product as selected by the user. The image processor in the copier is preferably further configured to receive the digital representations of the page sides of the original document from the computer readable memory as soon as the print engine is ready to receive the print-engine readable data set, thus providing for first-in/first-out document scanning and printing.
A second aspect of the invention is a method of duplex copying a plurality of sheets respectively having first and second sides defining page sides. The method includes the steps of scanning a first page side of one of the sheets to produce a first electronic image, scanning a second page side of one of the sheets to produce a second electronic image, and scanning a third page side of one of the sheets to produce a third electronic image. The method includes the step of commencing printing of a copy of the first electronic image of the first page side prior to scanning the third page side of one of the sheets.
In one embodiment of the second aspect of the invention, the document has at least three page sides (that is, at least two pages each having two page sides of interest). The method produces a copy product in which two page sides of the original document are printed on a single sheet of printable medium in the copy product, as selected by a user. The embodiment of method includes the step of providing a document scanner, a print buffer, and a print element. The method further includes the step of scanning a first page side of the document with the scanner to produce a first electronic data stream comprising discrete electronic representations of the first page side of the document. Thereafter, a second page side of the document is scanned to produce a second electronic data stream comprising discrete electronic representations of the second page side of the document. The electronic representations of the first and second page sides of the document are provided to a print buffer, which comprises a computer readable memory. From the print buffer, the discrete electronic representations of the first and second page sides of the document are sent to a print element. The method then includes the step of printing the discrete electronic representations of the first and second page sides of the document on a single sheet of printable medium such that the first page side of the document appears on the first side of a sheet of printable medium, and the second page side of the document appears on the second side of the sheet of printable medium. Alternately, the first page side of the original document can be stored in memory and then printed, after which the second page side is stored in memory and then printed.
Other features and advantages of the invention will become apparent to those of ordinary skill in the art upon review of the following detailed description, claims, and drawings.